1. Field of the Invention
The present invention relates to an automatic temperature rise control method for a molding machine such as an extrusion molding machine or an injection molding machine.
2. Description of the Related Art
In an injection molding machine as an example of molding machines, a screw is rotatably disposed inside a heating cylinder (a barrel), and is movable back and forth in an axial direction inside the heating cylinder. A nozzle (an outlet port) is provided in a tip end portion of the heating cylinder, and multiple heaters are disposed on an outer peripheral portion of the heating cylinder. A driving motor rotates the screw, and thereby moves the screw back and forth inside the heating cylinder. Thereby, the screw heats and melts resin chips as a raw material inputted from a hopper into the cylinder, and concurrently ejects the melted resin from the nozzle. Thus, the molding is performed.
In this type of the molding machine, the outer peripheral portion of the heating cylinder is divided into multiple heating sections (also referred to as heating zones) in the axial direction and the heaters are disposed at the respective heating sections. A temperature sensor is located in the vicinity of each of the heaters. A temperature measuring unit receives inputs from the temperature sensors. The temperatures of the heaters are controlled by use of the temperatures of the heating sections measured by the temperature measuring unit and target temperatures stored by a target temperature setting unit. For raising the temperatures of the respective heating sections, the heating section that requires the longest time to reach a preset target temperature is set as a master section while the heating sections other than this master section are set as slave sections.